1. Field of the Invention
The present invention relates to a power supply controller and an information processor. More particularly, the present invention relates to a power supply controller that directs a plurality of different voltages output from a power supply for use in different integrated circuits and to an information processor powered by the plurality of voltages.
2. Background of the Invention
A conventional information processor used in a personal computer requires a number of different voltages for normal operation. For example, an integrated circuit used in an information processor operates with a voltage according to the width of a signal line in the integrated circuit. In some cases, a single integrated circuit operates with a plurality of different voltages.
For every integrated circuit, a standard is provided which specifies the sequence for successively turning on multiple power supplies to safely distribute power to discrete circuits within an integrated circuit that operate on different voltages. For example, it is usually necessary to begin supplying a plurality of voltages sequentially, starting with a lower voltage. To turn off the supply of power the process is reversed, turning off the supply starting with a higher voltage, in order to prevent destruction or a malfunction of the integrated circuit.
The prior art includes a method of providing differential delay for a plurality of control signals used in power supply management. However, this method suffers from increased cost due to the need for additional delay circuits and increased circuit area dedicated to the power supply control function. Another prior art solution utilizes a microprocessor to control the timing of turn-on of each of a plurality of voltages. However, this method requires increased power consumption since even when no voltage is supplied to the information processor, the control microprocessor is driven in preparation for supplying a new voltage.